<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

<h2>Login page</h2>

<form action="" method="POST">
    Login: <input type="text" name="login" />
    <br/><br/>
    Password: <input type="text" name="password" />
    <br/><br/>
    <input type="submit" value="Login" />
    <c:if test="${error != null}">
        <br/><br/>
        <span style="color: red;">${error}</span>
    </c:if> 
</form>